[mojo]

hello.

i am trying to use ies spotlights in my scenes. it works fine with using small spheres for illuminating the room.

my problem is to visualize the light source itself. The small shining sphere hasn't the look of the spotlight...

how can i achieve that the spotlight looks real ?

thanks for your help,

mojo

[mojo]

with an ies file, which is shining in both directions ( down and a little bit up), i can illuminate the spotlight hole, too and it looks like a shining lightsource...

but i think there are more elegant ways to to it ?

[feynman]

You could try hiding the IES sphere from camera in Object Parameters > Appearance?

[mojo]

thats a good idea.

but what i want to achieve is that there is a white shining circle at the ceiling which is representing the spotlight itself. lets say 5 or 6 cm radius... and when i take an ies file which is only directed downwards, the "hole" in the ceiling stays dark.



http://s14.directupload.net/file/d/2865 ... gh_jpg.htm

[feynman]

Well, maybe the upwards directed illumination - as one can see from your IES diagram - is not sufficient to illuminate the semisphere/reflector above the IES emitter sphere? Maybe the material chosen is not quite right for a realistic reflector? You can always fake illumination perfectly well (in such tiny half-enclosed space as in a spotlight semisphere/reflector) with a gradient texture also...

[mojo]

well like i said, it works well with the settings like in the diagram.
The hole (reflector) surface has only a diffuse white ceiling material.

... but there should be a more elegant solution, shouldn't be ?

besides It reduces my range of possible ies-data.

or do i have to reconstruct the exact geometry of the lamp with reflectors etc ?
i want to keep it as simple as possible.

[feynman]

From my (still limited) experience, a lamp which is illuminated with an IES emitter light source renders realistic, if it is modeled realistic and if the assigned MXMs are realistic, meaning: if you have, for example, a nickel-plated aluminium reflector, modeled its geometry correctly with a nickel-plated aluminium MXM assigned, it will render realistically.

[eric nixon]

Sorry Feynman, it doesnt work like that, the ies will only give you the illumination pattern. Its normal to make the ies sphere hidden to cam and reflect/refract. then place an illuminated disc/geo which is only visible to cam if you need to see the lightsource itself.

[mojo]

hi eric,
thanks for your reply.

do you mean someting like this ?

http://s7.directupload.net/file/d/2865/gydpjys2_jpg.htm

[feynman]

Just out of interest, so we can improve, too - why would it not work by hiding the IES sphere from camera, etc. and modeling the reflector and other geometry (i.e. LED chip/fluo-tube, bezel, gasket, etc.) correctly, with realistically performing MXMs assigned? I always thought, the invisible IES emitter will thus light the lamp's & lightsource's geometry correctly?

[Bubbaloo]

Just out of interest, so we can improve, too - why would it not work by hiding the IES sphere from camera, etc. and modeling the reflector and other geometry (i.e. LED chip/fluo-tube, bezel, gasket, etc.) correctly, with realistically performing MXMs assigned? I always thought, the invisible IES emitter will thus light the lamp's & lightsource's geometry correctly?

In this case, you would not want to use the ies anymore. You would want to model the bulb or filament and place an emitter material on it. This is how we used to have to do it before ies support.

This is how I made this flashlight:

[feynman]

Nice, that gives a really convincing effect; I should drop the IES method then... (sorry, won't hijack this thread again).

[eric nixon]

Feynam, if you include a glass lens on your spot make sure its hidden to gi. The principle is IES gives you the light-distribution from the lamp NOT the lamp itself, simples...

Mojo yes thats it, just remember to hide the visible emitter from gi, or it will wash-out the ies.

[mojo]

thanks for your help!

[Primus]

Hi

I jump in with a short question ...

1 .When using "IES-light distribution" i have to use a small sphere, right ?
2. The size of the sphere has a deep influence about the illumination. So, how to size the sphere correctly ?

Best,
Tom